The present invention relates to a dental handpiece with a handle having one end connected to a supply hose. The latter has several supply lines for liquid or gaseous media. At the other end of the handle is located a head section with a dental tool. Hollow conductors are present in the handle for carrying the media from the supply channels to the head section. There is also provided means for achieving rotatability of the handle about its lengthwise axis relative to the supply hose, and for transfer of the media in the area of the parts threaded to one another.
With dental handpieces, to which liquid and/or gaseous media are supplied under pressure, e.g., with turbine handpieces, the handpiece at the instant of connection undergoes a sudden (jerklike) rotary motion which impairs the handling of the handpiece and makes difficult quiet and purposeful operation with the tool mounted on the head section. With a fixed (nonrotary) connection of handpiece and supply hose (mostly a threaded connection) the manipulating ability of the handpiece is severely restricted, particularly with shorter supply hose and higher pressure of the medium.
In order to avoid these disadvantages, it is already known in the art how to provide between the handpiece and the connecting fitting, with which the supply hose is fastened to the handpiece, a separate intermediate piece or element; this intermediate piece permits rotation of the handpiece abouts its lengthwise axis relative to the supply hose. The intermediate piece comprises two bodies of rotation which can be threaded together. With the peripheral surfaces facing one another, these bodies of rotation form annular channels (grooves) for transfer of the media from one body or rotation to the other. The annular channels (grooves) are sealed both against the outside and from each other by O-rings.
Such construction has the disadvantage that the hand-held instrument (handpiece plus intermediate piece) is relatively long and heavy and that the instrument hence becomes cumbersome. Due to the excess length of the instrument, there is exerted on the handpiece -- and to an increased extent on the tool mounted in the head section of the handpiece -- a pitching moment; to counteract the latter, a more solid grasping of the handle is required. However, the use of the handpiece for an appreciable time interval, such grasping leads to cramps in the fingers which should be avoided. Another disadvantage is that the construction to achieve rotatability of handpiece and supply hose is costly to manufacture.
It is therefore, an object of the present invention to provide a dental handpiece of the foregoing species which has a simpler construction and is hand-held more easily than the known types, and where during usage, no pitching moment with the aforementioned accompanying disadvantages can act on the handpiece.